The male and female parrotfish can be distinguished by characteristics such as body shape, color, and reproductive organs.
Body Shape and Color: Male parrotfish usually have a larger body size, a redder body color, and longer dorsal and anal fins, which sometimes can extend beyond the caudal fin. Female parrotfish, on the other hand, are smaller in size, have a lighter body color and are prone to turning white. Their dorsal and anal fins usually do not exceed the caudal fin. During the breeding season, the base of the caudal fin where it connects to the caudal peduncle and the part of the anal fin close to the caudal fin of male fish will turn red, while those of female fish will turn yellow.
Reproductive Organs: The genital pore area of male parrotfish is smooth, with a very small protruding part, and the abdomen is also smooth. However, the genital pore area of female parrotfish protrudes more obviously, and the abdomen will bulge slightly, which is even more noticeable during the breeding season.
Other Characteristics: Male parrotfish usually have a more aggressive temperament and are likely to develop a nuchal hump. Female parrotfish may also develop a nuchal hump before laying eggs, but this is not absolute. In addition, there are fleshy protuberances from the upper part of the abdomen to the front end of the dorsal fin in male fish, while female fish do not have them.
These characteristics will be more prominent during the breeding season, helping to identify the sex of parrotfish more accurately.